GIS Maps Prevent Vehicle Collisions with Elk and Deer

Arizona Department of Transportation uses GIS data to place crossings and underpasses.

Slamming a vehicle into an elk or deer is more harmful for humans than many realize. These creatures cause approximately 1.5 million collisions each year, resulting in around 150 deaths, according to the Insurance Institute for Highway Safety. Another 10,000 people suffer injuries from collisions with the animals.

Animal-car collisions can also cost governments money. For instance, the Arizona Department of Transportation (ADOT) has a financial stake in this problem because the state "owns" all wildlife, meaning the government is financially liable when an elk or deer obstructs a car or truck. The state paid more than $3 million for one such lawsuit in 2003.

For the past seven years, Arizona has been moving to solve the problem using a GIS tool that determines where deer and elk cross highways so underpasses can be built for the animals. Arizona's Game and Fish Department (AGFD) implemented the project in 2002 in partnership with ADOT, which funded most of the project.

Statistics suggest the program is effective. Deer and elk collisions dropped from 56 to eight on one major Arizona highway in one year after strategically placed underpasses were built, according to Jeff Gagnon, research technician for the AGFD. Another highway averaged 12 deer or elk accidents a year before it was targeted by the project; that highway has only seen one animal collision in the past two years, Gagnon said. The state hasn't yet measured what the project has done to the percentage of vehicle collisions statewide.

Gagnon said GIS helps his agency persuade ADOT to invest in the underpasses, which cost more than $1 million each. "They really buy into it when you pull out a map and say, 'This is where these animals are crossing,'" Gagnon said.

In 2004, ADOT and the AGFD organized the Arizona Wildlife Linkages Workgroup. This group expanded the project to include nine organizations with relevant input, such as the U.S. Department of Interior's Bureau of Land Management, the Federal Highway Administration, the U.S. Fish and Wildlife Service, Northern Arizona University, the Sky Island Alliance and other private environmental organizations. After pooling its resources, this team created a more developed GIS tool that's becoming a model for other states interested in solving animal-car collisions.

Animals Do the Legwork

Before Arizona could do a GIS analysis of where to install underpasses, officials needed data from the animals. Gagnon and others collared elk and deer with GPS devices. The resulting data showed animals crossing highways at areas where pastures or water waited on the other side. ADOT began installing underpasses. Conveniently some of them already existed for other purposes, like transporting water. GIS maps gave guidance to the state on how far to extend the fencing necessary for funneling the animals into the underpasses.

"We've had video cameras on some of those underpasses for about six years now. We've documented [more than] 6,000 animals using them. Most of those are elk, some deer -- 11 different species," Gagnon said. He added that even longhorn sheep and desert tortoises use the underpasses.

GIS technicians and fieldworkers attempting this in other states should expect to stay connected to the project throughout its life cycle, according to Susan Boe, GIS spatial analyst for the AGFD. With each highway the state converted for animal passage, she ran GIS tests of animal movements before, during and after construction. To run the analysis, Boe used ESRI's ArcGIS 9.2 software. To complete the job, she downloaded free software called Animal Movement, which is an extension of ESRI's ArcView application.

"Using Animal Movement, I was able to connect the dots to follow the path of movement," Boe explained. "It was what I used to find out where the animals were crossing the highway."

Arizona will use the project's findings to make informed decisions about where it builds future highways, Gagnon explained.

"If we're building a new highway, we could say, 'Hey, this meadow's going to cause problems. If we have options, let's take the highway over here,'" Gagnon said. ADOT would know from the beginning where it should build underpasses.

Race Against Time

A critical layer in Arizona's GIS tool was one identifying the different types of property owners connected to land alongside highways -- ADOT contributed that information. By viewing a GIS map, the Arizona Wildlife Linkages Workgroup saw what land was federally, privately and state owned, as well as what was part of an Indian reservation. This helped the team organize its time and resources more efficiently, because building underpasses on state-owned land comes with additional challenges. For example, Arizona's Constitution lets the state auction its land to commercial developers to raise money for public schools. In many cases, by the time the workgroup identified a parcel of state land that needed an underpass, the sale to the private sector was already in progress. This meant the Arizona State Land Department had to ensure the wildlife underpasses wouldn't conflict with the winning buyer's development plans.

"We're in a race against time. The land is getting developed fast. A lot of these plans started before we began our planning," said Bruce Eilerts, manager of the Natural Resources Management Group within ADOT.

Geographic data from nonprofit organizations also inform Arizona's GIS tool. Environmental groups on the team alert the workgroup to prospective sites for highway underpasses. For example, environmental groups alerted the workgroup to an expansion project on Highway 77 near Tucson, Ariz. ADOT was making changes to that highway, the environmental group said, that would increase vehicle collisions with animals.

"It wasn't something on our radar screen at first, but the community development is happening so fast up there," Eilerts explained. "The community was screaming about all of the wildlife hits and how it impacted the land and animals in the area, which had some state parks."

The environmental bodies in his workgroup coordinated meetings with community organizations from the area to develop a strategy for expanding Highway 77 without harming wildlife.

Save the Animals

Many view a state's wildlife as part of its identity. Gagnon cautioned that Arizona's growing population and busy roads will affect wildlife. "Once you put a highway in an area causing an animal to not cross the road very often, you isolate it," Gagnon said. "It can't get across to resources. It becomes genetically isolated, and if you genetically isolate the animals, they start to inbreed more. Instead of having two fawns they have one or none. They're more susceptible to diseases."

Eilerts said many European countries have killed off much of their wildlife due to property development.

"They actually have toad crossings in England and butterfly crossings in Germany," Eilerts said. "Good for them, but do we [the United States] want to wait until we're down to our field mice?"